Security Guidelines

We take security seriously. CodeIgniter incorporates a number of features and techniques to either enforce good security practices, or to enable you to do so easily.

We respect the Open Web Application Security Project (OWASP) and follow their recommendations as much as possible.

The following comes from OWASP Top Ten and OWASP API Security Top 10 identifying the top vulnerabilities for web applications and apis. For each, we provide a brief description, the OWASP recommendations, and then the CodeIgniter provisions to address the problem.

OWASP Top 10 2021

A01:2021 Broken Access Control

Access control enforces policy such that users cannot act outside of their intended permissions. Failures typically lead to unauthorized information disclosure, modification, or destruction of all data or performing a business function outside the user’s limits.

Common access control vulnerabilities include:

  • Violation of the principle of least privilege or deny by default, where access should only be granted for particular capabilities, roles, or users, but is available to anyone.

  • Bypassing access control checks by modifying the URL (parameter tampering or force browsing), internal application state, or the HTML page, or by using an attack tool modifying API requests.

  • Permitting viewing or editing someone else’s account, by providing its unique identifier (insecure direct object references)

  • Accessing API with missing access controls for POST, PUT and DELETE.

  • Elevation of privilege. Acting as a user without being logged in or acting as an admin when logged in as a user.

  • Metadata manipulation, such as replaying or tampering with a JSON Web Token (JWT) access control token, or a cookie or hidden field manipulated to elevate privileges or abusing JWT invalidation.

  • CORS misconfiguration allows API access from unauthorized/untrusted origins.

  • Force browsing to authenticated pages as an unauthenticated user or to privileged pages as a standard user.

OWASP recommendations

Access control is only effective in trusted server-side code or server-less API, where the attacker cannot modify the access control check or metadata.

  • Except for public resources, deny by default.

  • Implement access control mechanisms once and re-use them throughout the application, including minimizing Cross-Origin Resource Sharing (CORS) usage.

  • Model access controls should enforce record ownership rather than accepting that the user can create, read, update, or delete any record.

  • Unique application business limit requirements should be enforced by domain models.

  • Disable web server directory listing and ensure file metadata (e.g., .git) and backup files are not present within web roots.

  • Log access control failures, alert admins when appropriate (e.g., repeated failures).

  • Rate limit API and controller access to minimize the harm from automated attack tooling.

  • Stateful session identifiers should be invalidated on the server after logout. Stateless JWT tokens should rather be short-lived so that the window of opportunity for an attacker is minimized. For longer lived JWTs it’s highly recommended to follow the OAuth standards to revoke access.

CodeIgniter provisions

A02:2021 Cryptographic Failures

The first thing is to determine the protection needs of data in transit and at rest. For example, passwords, credit card numbers, health records, personal information, and business secrets require extra protection, mainly if that data falls under privacy laws, e.g., EU’s General Data Protection Regulation (GDPR), or regulations, e.g., financial data protection such as PCI Data Security Standard (PCI DSS). For all such data:

  • Is any data transmitted in clear text? This concerns protocols such as HTTP, SMTP, FTP also using TLS upgrades like STARTTLS. External internet traffic is hazardous. Verify all internal traffic, e.g., between load balancers, web servers, or back-end systems.

  • Are any old or weak cryptographic algorithms or protocols used either by default or in older code?

  • Are default crypto keys in use, weak crypto keys generated or re-used, or is proper key management or rotation missing? Are crypto keys checked into source code repositories?

  • Is encryption not enforced, e.g., are any HTTP headers (browser) security directives or headers missing?

  • Is the received server certificate and the trust chain properly validated?

  • Are initialization vectors ignored, reused, or not generated sufficiently secure for the cryptographic mode of operation? Is an insecure mode of operation such as ECB in use? Is encryption used when authenticated encryption is more appropriate?

  • Are passwords being used as cryptographic keys in absence of a password base key derivation function?

  • Is randomness used for cryptographic purposes that was not designed to meet cryptographic requirements? Even if the correct function is chosen, does it need to be seeded by the developer, and if not, has the developer over-written the strong seeding functionality built into it with a seed that lacks sufficient entropy/unpredictability?

  • Are deprecated hash functions such as MD5 or SHA1 in use, or are non-cryptographic hash functions used when cryptographic hash functions are needed?

  • Are deprecated cryptographic padding methods such as PKCS number 1 v1.5 in use?

  • Are cryptographic error messages or side channel information exploitable, for example in the form of padding oracle attacks?

OWASP recommendations

Do the following, at a minimum, and consult the references:

  • Classify data processed, stored, or transmitted by an application. Identify which data is sensitive according to privacy laws, regulatory requirements, or business needs.

  • Don’t store sensitive data unnecessarily. Discard it as soon as possible or use PCI DSS compliant tokenization or even truncation. Data that is not retained cannot be stolen.

  • Make sure to encrypt all sensitive data at rest.

  • Ensure up-to-date and strong standard algorithms, protocols, and keys are in place; use proper key management.

  • Encrypt all data in transit with secure protocols such as TLS with forward secrecy (FS) ciphers, cipher prioritization by the server, and secure parameters. Enforce encryption using directives like HTTP Strict Transport Security (HSTS).

  • Disable caching for response that contain sensitive data.

  • Apply required security controls as per the data classification.

  • Do not use legacy protocols such as FTP and SMTP for transporting sensitive data.

  • Store passwords using strong adaptive and salted hashing functions with a work factor (delay factor), such as Argon2, scrypt, bcrypt or PBKDF2.

  • Initialization vectors must be chosen appropriate for the mode of operation. For many modes, this means using a CSPRNG (cryptographically secure pseudo random number generator). For modes that require a nonce, then the initialization vector (IV) does not need a CSPRNG. In all cases, the IV should never be used twice for a fixed key.

  • Always use authenticated encryption instead of just encryption.

  • Keys should be generated cryptographically randomly and stored in memory as byte arrays. If a password is used, then it must be converted to a key via an appropriate password base key derivation function.

  • Ensure that cryptographic randomness is used where appropriate, and that it has not been seeded in a predictable way or with low entropy. Most modern APIs do not require the developer to seed the CSPRNG to get security.

  • Avoid deprecated cryptographic functions and padding schemes, such as MD5, SHA1, PKCS number 1 v1.5 .

  • Verify independently the effectiveness of configuration and settings.

CodeIgniter provisions

A03:2021 Injection

An application is vulnerable to attack when:

  • User-supplied data is not validated, filtered, or sanitized by the application.

  • Dynamic queries or non-parameterized calls without context-aware escaping are used directly in the interpreter.

  • Hostile data is used within object-relational mapping (ORM) search parameters to extract additional, sensitive records.

  • Hostile data is directly used or concatenated. The SQL or command contains the structure and malicious data in dynamic queries, commands, or stored procedures.

Some of the more common injections are SQL, NoSQL, OS command, Object Relational Mapping (ORM), LDAP, and Expression Language (EL) or Object Graph Navigation Library (OGNL) injection. The concept is identical among all interpreters. Source code review is the best method of detecting if applications are vulnerable to injections. Automated testing of all parameters, headers, URL, cookies, JSON, SOAP, and XML data inputs is strongly encouraged. Organizations can include static (SAST), dynamic (DAST), and interactive (IAST) application security testing tools into the CI/CD pipeline to identify introduced injection flaws before production deployment.

OWASP recommendations

Preventing injection requires keeping data separate from commands and queries:

  • The preferred option is to use a safe API, which avoids using the interpreter entirely, provides a parameterized interface, or migrates to Object Relational Mapping Tools (ORMs).

    • Note: Even when parameterized, stored procedures can still introduce SQL injection if PL/SQL or T-SQL concatenates queries and data or executes hostile data with EXECUTE IMMEDIATE or exec().

  • Use positive server-side input validation. This is not a complete defense as many applications require special characters, such as text areas or APIs for mobile applications.

  • For any residual dynamic queries, escape special characters using the specific escape syntax for that interpreter.

    • Note: SQL structures such as table names, column names, and so on cannot be escaped, and thus user-supplied structure names are dangerous. This is a common issue in report-writing software.

  • Use LIMIT and other SQL controls within queries to prevent mass disclosure of records in case of SQL injection.

CodeIgniter provisions

A04:2021 Insecure Design

Insecure design is a broad category representing different weaknesses, expressed as “missing or ineffective control design.” Insecure design is not the source for all other Top 10 risk categories. There is a difference between insecure design and insecure implementation. We differentiate between design flaws and implementation defects for a reason, they have different root causes and remediation.

A secure design can still have implementation defects leading to vulnerabilities that may be exploited. An insecure design cannot be fixed by a perfect implementation as by definition, needed security controls were never created to defend against specific attacks. One of the factors that contribute to insecure design is the lack of business risk profiling inherent in the software or system being developed, and thus the failure to determine what level of security design is required.

OWASP recommendations

  • Establish and use a secure development lifecycle with AppSec professionals to help evaluate and design security and privacy-related controls

  • Establish and use a library of secure design patterns or paved road ready to use components

  • Use threat modeling for critical authentication, access control, business logic, and key flows

  • Integrate security language and controls into user stories

  • Integrate plausibility checks at each tier of your application (from frontend to backend)

  • Write unit and integration tests to validate that all critical flows are resistant to the threat model. Compile use-cases and misuse-cases for each tier of your application.

  • Segregate tier layers on the system and network layers depending on the exposure and protection needs

  • Segregate tenants robustly by design throughout all tiers

  • Limit resource consumption by user or service

CodeIgniter provisions

A05:2021 Security Misconfiguration

The application might be vulnerable if the application is:

  • Missing appropriate security hardening across any part of the application stack or improperly configured permissions on cloud services.

  • Unnecessary features are enabled or installed (e.g., unnecessary ports, services, pages, accounts, or privileges).

  • Default accounts and their passwords are still enabled and unchanged.

  • Error handling reveals stack traces or other overly informative error messages to users.

  • For upgraded systems, the latest security features are disabled or not configured securely.

  • The security settings in the application servers, application frameworks (e.g., Struts, Spring, ASP.NET), libraries, databases, etc., are not set to secure values.

  • The server does not send security headers or directives, or they are not set to secure values.

  • The software is out of date or vulnerable (see A06:2021-Vulnerable and Outdated Components).

Without a concerted, repeatable application security configuration process, systems are at a higher risk.

OWASP recommendations

Secure installation processes should be implemented, including:

  • A repeatable hardening process makes it fast and easy to deploy another environment that is appropriately locked down. Development, QA, and production environments should all be configured identically, with different credentials used in each environment. This process should be automated to minimize the effort required to set up a new secure environment.

  • A minimal platform without any unnecessary features, components, documentation, and samples. Remove or do not install unused features and frameworks.

  • A task to review and update the configurations appropriate to all security notes, updates, and patches as part of the patch management process (see A06:2021-Vulnerable and Outdated Components). Review cloud storage permissions (e.g., S3 bucket permissions).

  • A segmented application architecture provides effective and secure separation between components or tenants, with segmentation, containerization, or cloud security groups (ACLs).

  • Sending security directives to clients, e.g., Security Headers.

  • An automated process to verify the effectiveness of the configurations and settings in all environments.

CodeIgniter provisions

A06:2021 Vulnerable and Outdated Components

You are likely vulnerable:

  • If you do not know the versions of all components you use (both client-side and server-side). This includes components you directly use as well as nested dependencies.

  • If the software is vulnerable, unsupported, or out of date. This includes the OS, web/application server, database management system (DBMS), applications, APIs and all components, runtime environments, and libraries.

  • If you do not scan for vulnerabilities regularly and subscribe to security bulletins related to the components you use.

  • If you do not fix or upgrade the underlying platform, frameworks, and dependencies in a risk-based, timely fashion. This commonly happens in environments when patching is a monthly or quarterly task under change control, leaving organizations open to days or months of unnecessary exposure to fixed vulnerabilities.

  • If software developers do not test the compatibility of updated, upgraded, or patched libraries.

  • If you do not secure the components’ configurations (see A05:2021-Security Misconfiguration).

OWASP recommendations

There should be a patch management process in place to:

  • Remove unused dependencies, unnecessary features, components, files, and documentation.

  • Continuously inventory the versions of both client-side and server-side components (e.g., frameworks, libraries) and their dependencies using tools like versions, OWASP Dependency Check, retire.js, etc. Continuously monitor sources like Common Vulnerability and Exposures (CVE) and National Vulnerability Database (NVD) for vulnerabilities in the components. Use software composition analysis tools to automate the process. Subscribe to email alerts for security vulnerabilities related to components you use.

  • Only obtain components from official sources over secure links. Prefer signed packages to reduce the chance of including a modified, malicious component (See A08:2021-Software and Data Integrity Failures).

  • Monitor for libraries and components that are unmaintained or do not create security patches for older versions. If patching is not possible, consider deploying a virtual patch to monitor, detect, or protect against the discovered issue.

Every organization must ensure an ongoing plan for monitoring, triaging, and applying updates or configuration changes for the lifetime of the application or portfolio.

CodeIgniter provisions

A07:2021 Identification and Authentication Failures

Confirmation of the user’s identity, authentication, and session management is critical to protect against authentication-related attacks. There may be authentication weaknesses if the application:

  • Permits automated attacks such as credential stuffing, where the attacker has a list of valid usernames and passwords.

  • Permits brute force or other automated attacks.

  • Permits default, weak, or well-known passwords, such as “Password1” or “admin/admin”.

  • Uses weak or ineffective credential recovery and forgot-password processes, such as “knowledge-based answers,” which cannot be made safe.

  • Uses plain text, encrypted, or weakly hashed passwords data stores (see A02:2021-Cryptographic Failures).

  • Has missing or ineffective multi-factor authentication.

  • Exposes session identifier in the URL.

  • Reuse session identifier after successful login.

  • Does not correctly invalidate Session IDs. User sessions or authentication tokens (mainly single sign-on (SSO) tokens) aren’t properly invalidated during logout or a period of inactivity.

OWASP recommendations

  • Where possible, implement multi-factor authentication to prevent automated credential stuffing, brute force, and stolen credential reuse attacks.

  • Do not ship or deploy with any default credentials, particularly for admin users.

  • Implement weak password checks, such as testing new or changed passwords against the top 10,000 worst passwords list.

  • Align password length, complexity, and rotation policies with National Institute of Standards and Technology (NIST) 800-63b’s guidelines in section 5.1.1 for Memorized Secrets or other modern, evidence-based password policies.

  • Ensure registration, credential recovery, and API pathways are hardened against account enumeration attacks by using the same messages for all outcomes.

  • Limit or increasingly delay failed login attempts, but be careful not to create a denial of service scenario. Log all failures and alert administrators when credential stuffing, brute force, or other attacks are detected.

  • Use a server-side, secure, built-in session manager that generates a new random session ID with high entropy after login. Session identifier should not be in the URL, be securely stored, and invalidated after logout, idle, and absolute timeouts.

CodeIgniter provisions

A08:2021 Software and Data Integrity Failures

Software and data integrity failures relate to code and infrastructure that does not protect against integrity violations. An example of this is where an application relies upon plugins, libraries, or modules from untrusted sources, repositories, and content delivery networks (CDNs). An insecure CI/CD pipeline can introduce the potential for unauthorized access, malicious code, or system compromise.

Lastly, many applications now include auto-update functionality, where updates are downloaded without sufficient integrity verification and applied to the previously trusted application. Attackers could potentially upload their own updates to be distributed and run on all installations.

Another example is where objects or data are encoded or serialized into a structure that an attacker can see and modify is vulnerable to insecure deserialization.

OWASP recommendations

  • Use digital signatures or similar mechanisms to verify the software or data is from the expected source and has not been altered.

  • Ensure libraries and dependencies, such as npm or Maven, are consuming trusted repositories. If you have a higher risk profile, consider hosting an internal known-good repository that’s vetted.

  • Ensure that a software supply chain security tool, such as OWASP Dependency Check or OWASP CycloneDX, is used to verify that components do not contain known vulnerabilities

  • Ensure that there is a review process for code and configuration changes to minimize the chance that malicious code or configuration could be introduced into your software pipeline.

  • Ensure that your CI/CD pipeline has proper segregation, configuration, and access control to ensure the integrity of the code flowing through the build and deploy processes.

  • Ensure that unsigned or unencrypted serialized data is not sent to untrusted clients without some form of integrity check or digital signature to detect tampering or replay of the serialized data

CodeIgniter provisions

  • n/a

A09:2021 Security Logging and Monitoring Failures

This category is to help detect, escalate, and respond to active breaches. Without logging and monitoring, breaches cannot be detected. Insufficient logging, detection, monitoring, and active response occurs any time:

  • Auditable events, such as logins, failed logins, and high-value transactions, are not logged.

  • Warnings and errors generate no, inadequate, or unclear log messages.

  • Logs of applications and APIs are not monitored for suspicious activity.

  • Logs are only stored locally.

  • Appropriate alerting thresholds and response escalation processes are not in place or effective.

  • Penetration testing and scans by dynamic application security testing (DAST) tools (such as OWASP ZAP) do not trigger alerts.

  • The application cannot detect, escalate, or alert for active attacks in real-time or near real-time.

You are vulnerable to information leakage by making logging and alerting events visible to a user or an attacker (see A01:2021-Broken Access Control).

OWASP recommendations

Developers should implement some or all the following controls, depending on the risk of the application:

  • Ensure all login, access control, and server-side input validation failures can be logged with sufficient user context to identify suspicious or malicious accounts and held for enough time to allow delayed forensic analysis.

  • Ensure that logs are generated in a format that log management solutions can easily consume.

  • Ensure log data is encoded correctly to prevent injections or attacks on the logging or monitoring systems.

  • Ensure high-value transactions have an audit trail with integrity controls to prevent tampering or deletion, such as append-only database tables or similar.

  • DevSecOps teams should establish effective monitoring and alerting such that suspicious activities are detected and responded to quickly.

  • Establish or adopt an incident response and recovery plan, such as National Institute of Standards and Technology (NIST) 800-61r2 or later.

There are commercial and open-source application protection frameworks such as the OWASP ModSecurity Core Rule Set, and open-source log correlation software, such as the Elasticsearch, Logstash, Kibana (ELK) stack, that feature custom dashboards and alerting.

CodeIgniter provisions

A10:2021 Server-Side Request Forgery (SSRF)

SSRF flaws occur whenever a web application is fetching a remote resource without validating the user-supplied URL. It allows an attacker to coerce the application to send a crafted request to an unexpected destination, even when protected by a firewall, VPN, or another type of network access control list (ACL).

As modern web applications provide end-users with convenient features, fetching a URL becomes a common scenario. As a result, the incidence of SSRF is increasing. Also, the severity of SSRF is becoming higher due to cloud services and the complexity of architectures.

OWASP recommendations

Developers can prevent SSRF by implementing some or all the following defense in depth controls:

From Network layer:

  • Segment remote resource access functionality in separate networks to reduce the impact of SSRF

  • Enforce “deny by default” firewall policies or network access control rules to block all but essential intranet traffic.

    • Hints:

      • Establish an ownership and a lifecycle for firewall rules based on applications.

      • Log all accepted and blocked network flows on firewalls (see A09:2021-Security Logging and Monitoring Failures).

From Application layer:

  • Sanitize and validate all client-supplied input data

  • Enforce the URL schema, port, and destination with a positive allow list

  • Do not send raw responses to clients

  • Disable HTTP redirections

  • Be aware of the URL consistency to avoid attacks such as DNS rebinding and “time of check, time of use” (TOCTOU) race conditions

Do not mitigate SSRF via the use of a deny list or regular expression. Attackers have payload lists, tools, and skills to bypass deny lists.

CodeIgniter provisions

OWASP API Security Top 10 2023

API1:2023 Broken Object Level Authorization

APIs tend to expose endpoints that handle object identifiers, creating a wide attack surface of Object Level Access Control issues. Object level authorization checks should be considered in every function that accesses a data source using an ID from the user.

OWASP recommendations

  • Implement a proper authorization mechanism that relies on the user policies and hierarchy.

  • Use the authorization mechanism to check if the logged-in user has access to perform the requested action on the record in every function that uses an input from the client to access a record in the database.

  • Prefer the use of random and unpredictable values as GUIDs for records’ IDs.

  • Write tests to evaluate the vulnerability of the authorization mechanism. Do not deploy changes that make the tests fail.

CodeIgniter provisions

API2:2023 Broken Authentication

Authentication mechanisms are often implemented incorrectly, allowing attackers to compromise authentication tokens or to exploit implementation flaws to assume other user’s identities temporarily or permanently. Compromising a system’s ability to identify the client/user, compromises API security overall.

OWASP recommendations

  • Make sure you know all the possible flows to authenticate to the API (mobile/ web/deep links that implement one-click authentication/etc.). Ask your engineers what flows you missed.

  • Read about your authentication mechanisms. Make sure you understand what and how they are used. OAuth is not authentication, and neither are API keys.

  • Don’t reinvent the wheel in authentication, token generation, or password storage. Use the standards.

  • Credential recovery/forgot password endpoints should be treated as login endpoints in terms of brute force, rate limiting, and lockout protections.

  • Require re-authentication for sensitive operations (e.g. changing the account owner email address/2FA phone number).

  • Use the OWASP Authentication Cheatsheet.

  • Where possible, implement multi-factor authentication.

  • Implement anti-brute force mechanisms to mitigate credential stuffing, dictionary attacks, and brute force attacks on your authentication endpoints. This mechanism should be stricter than the regular rate limiting mechanisms on your APIs.

  • Implement account lockout/captcha mechanisms to prevent brute force attacks against specific users. Implement weak-password checks.

  • API keys should not be used for user authentication. They should only be used for API clients authentication.

CodeIgniter provisions

API3:2023 Broken Object Property Level Authorization

This category combines API3:2019 Excessive Data Exposure and API6:2019 - Mass Assignment, focusing on the root cause: the lack of or improper authorization validation at the object property level. This leads to information exposure or manipulation by unauthorized parties.

OWASP recommendations

  • When exposing an object using an API endpoint, always make sure that the user should have access to the object’s properties you expose.

  • Avoid using generic methods such as to_json() and to_string(). Instead, cherry-pick specific object properties you specifically want to return.

  • If possible, avoid using functions that automatically bind a client’s input into code variables, internal objects, or object properties (“Mass Assignment”).

  • Allow changes only to the object’s properties that should be updated by the client.

  • Implement a schema-based response validation mechanism as an extra layer of security. As part of this mechanism, define and enforce data returned by all API methods.

  • Keep returned data structures to the bare minimum, according to the business/functional requirements for the endpoint.

CodeIgniter provisions

API4:2023 Unrestricted Resource Consumption

Satisfying API requests requires resources such as network bandwidth, CPU, memory, and storage. Other resources such as emails/SMS/phone calls or biometrics validation are made available by service providers via API integrations, and paid for per request. Successful attacks can lead to Denial of Service or an increase of operational costs.

OWASP recommendations

  • Use a solution that makes it easy to limit memory, CPU, number of restarts, file descriptors, and processes such as Containers / Serverless code (e.g. Lambdas).

  • Define and enforce a maximum size of data on all incoming parameters and payloads, such as maximum length for strings, maximum number of elements in arrays, and maximum upload file size (regardless of whether it is stored locally or in cloud storage).

  • Implement a limit on how often a client can interact with the API within a defined timeframe (rate limiting).

  • Rate limiting should be fine tuned based on the business needs. Some API Endpoints might require stricter policies.

  • Limit/throttle how many times or how often a single API client/user can execute a single operation (e.g. validate an OTP, or request password recovery without visiting the one-time URL).

  • Add proper server-side validation for query string and request body parameters, specifically the one that controls the number of records to be returned in the response.

  • Configure spending limits for all service providers/API integrations. When setting spending limits is not possible, billing alerts should be configured instead.

CodeIgniter provisions

API5:2023 Broken Function Level Authorization

Complex access control policies with different hierarchies, groups, and roles, and an unclear separation between administrative and regular functions, tend to lead to authorization flaws. By exploiting these issues, attackers can gain access to other users’ resources and/or administrative functions.

OWASP recommendations

Your application should have a consistent and easy-to-analyze authorization module that is invoked from all your business functions. Frequently, such protection is provided by one or more components external to the application code.

  • The enforcement mechanism(s) should deny all access by default, requiring explicit grants to specific roles for access to every function.

  • Review your API endpoints against function level authorization flaws, while keeping in mind the business logic of the application and groups hierarchy.

  • Make sure that all of your administrative controllers inherit from an administrative abstract controller that implements authorization checks based on the user’s group/role.

  • Make sure that administrative functions inside a regular controller implement authorization checks based on the user’s group and role.

CodeIgniter provisions

API6:2023 Unrestricted Access to Sensitive Business Flows

APIs vulnerable to this risk expose a business flow - such as buying a ticket, or posting a comment - without compensating for how the functionality could harm the business if used excessively in an automated manner. This doesn’t necessarily come from implementation bugs.

OWASP recommendations

The mitigation planning should be done in two layers:

  • Business - identify the business flows that might harm the business if they are excessively used.

  • Engineering - choose the right protection mechanisms to mitigate the business risk.

Some of the protection mechanisms are more simple while others are more difficult to implement. The following methods are used to slow down automated threats:

  • Device fingerprinting: denying service to unexpected client devices (e.g headless browsers) tends to make threat actors use more sophisticated solutions, thus more costly for them

  • Human detection: using either captcha or more advanced biometric solutions (e.g. typing patterns)

  • Non-human patterns: analyze the user flow to detect non-human patterns (e.g. the user accessed the “add to cart” and “complete purchase” functions in less than one second)

  • Consider blocking IP addresses of Tor exit nodes and well-known proxies

Secure and limit access to APIs that are consumed directly by machines (such as developer and B2B APIs). They tend to be an easy target for attackers because they often don’t implement all the required protection mechanisms.

CodeIgniter provisions

  • n/a

API7:2023 Server Side Request Forgery

Server-Side Request Forgery (SSRF) flaws can occur when an API is fetching a remote resource without validating the user-supplied URI. This enables an attacker to coerce the application to send a crafted request to an unexpected destination, even when protected by a firewall or a VPN.

OWASP recommendations

  • Isolate the resource fetching mechanism in your network: usually these features are aimed to retrieve remote resources and not internal ones.

  • Whenever possible, use allow lists of:

    • Remote origins users are expected to download resources from (e.g. Google Drive, Gravatar, etc.)

    • URL schemes and ports

    • Accepted media types for a given functionality

  • Disable HTTP redirections.

  • Use a well-tested and maintained URL parser to avoid issues caused by URL parsing inconsistencies.

  • Validate and sanitize all client-supplied input data.

  • Do not send raw responses to clients.

CodeIgniter provisions

API8:2023 Security Misconfiguration

APIs and the systems supporting them typically contain complex configurations, meant to make the APIs more customizable. Software and DevOps engineers can miss these configurations, or don’t follow security best practices when it comes to configuration, opening the door for different types of attacks.

OWASP recommendations

The API life cycle should include:

  • A repeatable hardening process leading to fast and easy deployment of a properly locked down environment

  • A task to review and update configurations across the entire API stack. The review should include: orchestration files, API components, and cloud services (e.g. S3 bucket permissions)

  • An automated process to continuously assess the effectiveness of the configuration and settings in all environments


  • Ensure that all API communications from the client to the API server and any downstream/upstream components happen over an encrypted communication channel (TLS), regardless of whether it is an internal or public-facing API.

  • Be specific about which HTTP verbs each API can be accessed by: all other HTTP verbs should be disabled (e.g. HEAD).

  • APIs expecting to be accessed from browser-based clients (e.g., WebApp front-end) should, at least:

    • implement a proper Cross-Origin Resource Sharing (CORS) policy

    • include applicable Security Headers

  • Restrict incoming content types/data formats to those that meet the business/ functional requirements.

  • Ensure all servers in the HTTP server chain (e.g. load balancers, reverse and forward proxies, and back-end servers) process incoming requests in a uniform manner to avoid desync issues.

  • Where applicable, define and enforce all API response payload schemas, including error responses, to prevent exception traces and other valuable information from being sent back to attackers.

CodeIgniter provisions

API9:2023 Improper Inventory Management

APIs tend to expose more endpoints than traditional web applications, making proper and updated documentation highly important. A proper inventory of hosts and deployed API versions also are important to mitigate issues such as deprecated API versions and exposed debug endpoints.

OWASP recommendations

  • Inventory all API hosts and document important aspects of each one of them, focusing on the API environment (e.g. production, staging, test, development), who should have network access to the host (e.g. public, internal, partners) and the API version.

  • Inventory integrated services and document important aspects such as their role in the system, what data is exchanged (data flow), and their sensitivity.

  • Document all aspects of your API such as authentication, errors, redirects, rate limiting, cross-origin resource sharing (CORS) policy, and endpoints, including their parameters, requests, and responses.

  • Generate documentation automatically by adopting open standards. Include the documentation build in your CI/CD pipeline.

  • Make API documentation available only to those authorized to use the API.

  • Use external protection measures such as API security specific solutions for all exposed versions of your APIs, not just for the current production version.

  • Avoid using production data with non-production API deployments. If this is unavoidable, these endpoints should get the same security treatment as the production ones.

  • When newer versions of APIs include security improvements, perform a risk analysis to inform the mitigation actions required for the older versions. For example, whether it is possible to backport the improvements without breaking API compatibility or if you need to take the older version out quickly and force all clients to move to the latest version.

CodeIgniter provisions

API10:2023 Unsafe Consumption of APIs

Developers tend to trust data received from third-party APIs more than user input, and so tend to adopt weaker security standards. In order to compromise APIs, attackers go after integrated third-party services instead of trying to compromise the target API directly.

OWASP recommendations

  • When evaluating service providers, assess their API security posture.

  • Ensure all API interactions happen over a secure communication channel (TLS).

  • Always validate and properly sanitize data received from integrated APIs before using it.

  • Maintain an allowlist of well-known locations integrated APIs may redirect yours to: do not blindly follow redirects.

CodeIgniter provisions